1. Field of the Invention
The invention relates in general to a control method and device for an image signal, and more particularly, to a method and device for controlling a subtitle applied to a display apparatus.
2. Description of the Related Art
With the spur of three-dimensional (3D) movies, related products such as 3D televisions have also begun to prosper. After receiving an image signal generated by a 3D image source (e.g., a player supporting 3D images), the 3D television displays the 3D image according to the image signal, offering a viewer the pleasure of viewing a 3D movie.
In general, after receiving an image signal, a 3D television alternately displays a left-eye frame and a right-eye frame on a screen and correspondingly shields a left eye and a right eye of a viewer in an alternate manner. Alternatively, the left-eye frame and the right-eye frame are played in a row interlaced format, and a micro polarizer is utilized by a viewer to allow a left eye of the viewer to perceive the left-eye frame and a right eye of the viewer to perceive the right-eye frame. Due to minute differences between objects in the left-eye and right-eye frames, the viewer is then enabled to observe a 3D movie with increased visual depth perception.
While filming image signals, a same object is filmed by two video cameras located at different positions. A first video camera captures a left-eye frame, and a second video camera captures a right-eye frame. In a post-process of the image signals, in addition to processing the left-eye and right-eye frames by the foregoing temporally alternating and row interlacing approaches, a subtitle can be selectively added to the left-eye and right-eye frames to further interpret dialog content of the images. Once the image signals are post-processed, a 3D image source transmits the image signals to a 3D television, which then plays a corresponding 3D movie according to the image signals.
In some image signals outputted by a 3D source, a subtitle is already added to a predetermined position in the left-eye and right-eye frames. However, in conventional 3D television processing mechanisms, the position and image properties of the subtitle in the left-eye and right-eye frames are inalterable. For example, a 2D subtitle cannot be changed to a 3D subtitle.
In other words, when image signals outputted from a 3D image source are already attached with a subtitle, a current 3D television merely serves as a receiver of the image signals, incapable of changing the position and image properties of the subtitle. In this way, a viewer may not timely adapt to a display mode of a subtitle when viewing a 3D movie under certain circumstances, and thus suffer from extreme eye discomfort and fatigue.